1. Field
The present invention relates to an improvement (temperature compensation) in white balance in an imaging device such as an imaging device using a 3-CCD.
2. Description of the Related Art
It is known that an imaging device using a 3-CCD tends to lose white balance because of temperature rises in CCDs for R, G, and B.
Under such circumstances, there has already been proposed a method of inhibiting a change in the white balance in the imaging device using the CCD.
Japanese Patent Application Publication (KOKAI) No. Hei-1-259692 (first document) discloses a single-element solid-state imaging element, wherein the imaging elements are attached to a substrate, and heat of the substrate is radiated so that the imaging elements for R, G, and B may be uniform in temperature to restore the white balance.
Japanese Patent Application Publication (KOKAI) No. Hei-5-207486 (second document) discloses a solid-state imaging element of a 3-CCD using a color separation prism, wherein the imaging elements (R, G, and B) are cooled by an electronic cooler.
Japanese Patent Application Publication (KOKAI) No. 2008-72439 (third document) discloses an image processing apparatus which corrects the loss of the white balance in a CMOS sensor due to a temperature change, in accordance with the difference between a temperature during factory coordination and a current temperature.
The solid-state imaging element shown in the first document is an only one-element type, and there is no statement about the elimination of the loss of white balance due to a temperature rise in each element or due to a change in the sensitivity of each element caused by a temperature rise in the case where imaging elements for R, G, and B are independently provided.
The electronic cooler shown in the second document is known to be highly expensive and to increase an overall size (volume).
The image processing apparatus shown in the third document corrects the white balance in accordance with the difference between a temperature during factory coordination and a current temperature (in an installation environment), when driving the CMOS sensor. However, there is no statement about the elimination of the loss of the white balance due to the difference in temperature rise among the elements in the case where the imaging elements for R, G, and B are independently provided.